Known in the art are pneumatic percussive tools, wherein a vibration damping device secured to the lower portion of the tool casing comprises a sleeve having a working tool which is received therein and has a piston which divides the interior of the sleeve into two chambers of which one chamber behind the piston communicates with the working chamber of the pneumatic tool, and the other chamber in front of the piston communicates with atmosphere. This construction of the vibration damping device in a pneumatic percussive tool is disadvantageous in that the provision of a piston on the working tool complicates the tool and makes it more expensive. In addition, constant soiling of working surfaces of the piston and sleeve results in a rapid wear thereof so that the tightness of the chamber behind the piston is lost, and the working tool which recoils from the workpiece breaks through the air cushion of the chamber in front of the piston and hits directly against the tool casing (cf. USSR Inventor's Certificate No. 338362).
Known in art is also a pneumatic percussive tool comprising a barrel having an annular groove in the front end portion and a hammer piston in the barrel, a working tool received in the barrel for axial movement, a floating sleeve which is axially movable and which surrounds the working tool, a damping chamber defined by opposite end faces of the floating sleeve and barrel, respectively, which communicates with a compressed air source and has an outer annular projection (cf. USSR Inventor's Certificate No. 712245).
Though this device is more reliable than that described above, it is deficient in that when the working tool is jammed in the floating sleeve, the blows are transmitted through the sleeve to the tool casing thus bringing about increased vibrations acting on the operator.